Toxicity and Synergistic Effect of Native Plants Extracts against the Cowpea Weevil (Callosobruchus maculatus Fab.) (Coleoptera: Bruchidae)
Elias Mano
*
Institut de Recherche en Sciences Appliquées et Technologies (IRSAT), P. Box 2393 Bobo Dioulasso, Burkina Faso and 'Institut de l'Environnement et de Recherches Agricoles du Burkina Faso (INERA), Laboratoire Central d'Horticulture du Centre Régional d'Excellence en Fruits et Légumes, Bobo-Dioulasso, Burkina Faso.
Nadjatou Ouédraogo
Ecole Nationale de Formation Agricole of Matourkou (ENAFA), Bobo Dioulasso, Burkina Faso.
Rabièta Simdé
'Institut de l'Environnement et de Recherches Agricoles du Burkina Faso (INERA), Laboratoire Central d'Horticulture du Centre Régional d'Excellence en Fruits et Légumes, Bobo-Dioulasso, Burkina Faso.
Désiré Dramane Ak Sanou
Université Nazi Boni / Institute du Development Rural (IDR), Bobo Dioulasso, Burkina Faso.
Rasmané Abdou Ouédraogo
Institut de Recherche en Sciences Appliquées et Technologies (IRSAT), P. Box 2393 Bobo Dioulasso, Burkina Faso and 'Institut de l'Environnement et de Recherches Agricoles du Burkina Faso (INERA), Laboratoire Central d'Horticulture du Centre Régional d'Excellence en Fruits et Légumes, Bobo-Dioulasso, Burkina Faso.
Boubakar Ouattara
'Institut de l'Environnement et de Recherches Agricoles du Burkina Faso (INERA), Laboratoire Central d'Horticulture du Centre Régional d'Excellence en Fruits et Légumes, Bobo-Dioulasso, Burkina Faso.
Pierre Alexandre Eric Djifaby Sombié
'Institut de l'Environnement et de Recherches Agricoles du Burkina Faso (INERA), Laboratoire Central d'Horticulture du Centre Régional d'Excellence en Fruits et Légumes, Bobo-Dioulasso, Burkina Faso.
Souleymane Nacro
'Institut de l'Environnement et de Recherches Agricoles du Burkina Faso (INERA), Laboratoire Central d'Horticulture du Centre Régional d'Excellence en Fruits et Légumes, Bobo-Dioulasso, Burkina Faso.
*Author to whom correspondence should be addressed.
Abstract
Callosobruchus maculatus causes loss of cowpea seeds and its weight after six months of unprotected storage. This study aimed to evaluate the toxicity and synergistic effects of plant extracts on the biological parameters of C. maculatus from Bobo Dioulasso in order to reduce its damage on cowpea stocks in Bobo Dioulasso city. Seven treatments including an untreated control and doses of three powdery extracts of Cassia nigricans, Zanthoxylum zanthoxyloides and Hyptis suaveolens, and their combinations were compared in a Fischer block with four completely randomized repetitions. One hundred healthy cowpea seeds were mixed with doses of each extract in Petri dishes then submitted as food substrates to ten pairs of C. maculatus for 15 days. The synergistic effect was evaluated following the formula of Chou and Talalay. Extracts of C. nigricans, Z. zanthoxyloides and H. suaveolens was toxic against the weevil. The extract of Z. zanthoxyloides was more toxic to adults (21.16 mg/g) followed by H. suaveolens (51.84 mg/g) and C. nigricans (52.09 mg/g). The infestation rates of batches treated with C. nigricans and Z. zanthoxyloides extracts did not exceed 1.00% compared to 2.00% for H. suaveolens at 20 mg/g. All combinations were synergistic and resulted in 100% mortality and less than 14.98 eggs/female in H. suaveolens coupled with C. nigricans. The application of Z. zanthoxyloides extract alone or the combination of H. suaveolens and C. nigricans extracts would be an alternative for the sustainable management of C. maculatus in cowpea stocks.
Keywords: Zanthoxylum zanthoxyloides, cassia nigricans, hyptis suaveolens, insecticidal activity, stored seed